Combination blower, trimmer and edger for tending vegetation

ABSTRACT

An engine is connected to the upper end of a drive shaft housing and a work head with a string trimmer or blower or both is operatively connected to the lower end of the drive shaft housing and is rotatably driven by an engine rotating a drive shaft inside the drive shaft housing and connected to the working head. The drive shaft housing is rigidly connected to the working head and may be rotated about its longitudinal axis relative to the engine in any desired amount of rotation, but the preferred degree of rotation is 135° to move the working head from a trimming position with the rotating trimmer string in a horizontal position to an edging position with the rotating trimmer string in a vertical position and with the working head being displaced to the operator&#39;s right side for better viewing and control and operator comfort. In one embodiment, a gear driven crank handle is rigidly connected to the drive shaft housing and is itself rotated 135° as the drive shaft housing is rotated 135° to place the handle in a position that is comfortable to use. Further, the amount of air flowing through the blower is regulated by an air outlet regulating valve and a separate air intake regulating valve.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

STATEMENT REGARDING A SEQUENCE LISTING

Not applicable.

BACKGROUND OF THE INVENTION

The present invention is related to an apparatus for facilitating lawntrimming care. More particularly, the present invention combines ablower inside a housing having an exit blower duct and a string trimmerhead, both driven simultaneously by a motor connected to a drive shaft.Novel handles facilitate rotating the apparatus into a trimming mode oran edging mode and air flow control valves regulate the volume of airflowing through the blower.

DESCRIPTION OF THE RELATED ART INCLUDING INFORMATION DISCLOSED UNDER 37C.F.R.1.97 AND 1.98

Complete lawn care now typically includes trimming areas that lawnmowers cannot access easily; edging vegetation along defined perimeters,such as curbs; and removing the vegetation debris, such as lawntrimmings or fallen leaves, from areas where they are not wanted, suchas sidewalks and driveways, typically by blowing them away to an areawhere they will not be seen, such as the lawn. Carrying out theseseparate tasks has traditionally required different and separate tools,namely, a lawn mower, a string trimmer, an edger and a blower.

In commercial applications particularly, such as grooming golf courses,the necessity for using different and separate tools for these tasksleads to lost time and inefficiency because workers must return to atool shed or truck, often located at some distance from the workers, toretrieve the appropriate tool. A worker may carry and use a particulartool, for example, a string trimmer, for several hours without pause,leading him far from his tool shed or truck. The worker cannot carry allthese different tools with him due to their bulk and weight.

Further, many workers remove the debris shield from string trimmers toprovide a better view of the work area, but the debris shield isdesigned to help prevent flying debris from striking the worker in theeyes or other sensitive areas.

Combining the functionality of some of these separate tools into asingle tool would save time and money, including capital outlay for thetools.

Further, when a conventional string trimmer is used for edging, the usertypically twists his body into an unnatural, uncomfortable and dangerousposture and usually walks backward to accomplish edging, in which thetrimmer is held so that the rotating trimming string rotates basicallyin a vertical plane. It would be safer to provide a string trimmer thatcan be rotated into a natural position that allows the trimmer string torotate in a vertical plane.

Some efforts in that direction have been taken. For example, U.S. Pat.No. 4,773,471 discloses separate operating heads, such as a stringtrimmer head or a blower head, that can be attached and detached fromthe same power plant and drive train, saving the expense of a secondmotor. This system still requires that a significant subassembly of thetool be removed and replaced by another tool, requiring the worker tocarry separate tools and to change operating heads on the tool. Thissystem has the same disadvantages as having separate tools when they areused.

U.S. Pat. No. 4,187,577 discloses a blower chute that can be strappedonto the bottom of a string trimmer with a bungee cord, but does notallow the string trimmer function to be used when the blower attachmentis installed, requiring the operator to carry separate subsystems andinstall and remove them to carry out the separate functions of trimmingand blowing.

U.S. Patent Application Publication Number US 2002/0007559 discloses astring trimmer with a specially designed shroud that is supposed to helpthe rotating string of the string trimmer to function as a blower. Whileit has long been known that the rotating string of the string trimmerprovides some blowing forces, they tend to be non-directional, producinggreater drag on the engine than a small blower would, and even thisreference discloses that any blowing action is basically downward andoutward from the rotating string, which provides little benefit indebris removal from sidewalks and so forth. Further, any blowing forcegenerated by the rotating string is minimal and will not move debris anysignificant distance.

U.S. Pat. No. 6,442,845 discloses a string trimmer that can be convertedto a blade trimmer and that can be modified to attach a blower flute orscroll to direct air flow generated by a cooling fin that is part of thestring trimmer spool and designed to cool the motor of the apparatus.The use of this fan in a attempt to create a blower function isinadequate because it utilizes a fan that is designed only for motorcooling and is structurally a part of a string trimmer head, limitingits utility for actually blowing debris, due to its position and its useto cool the motor. A string trimmer head that does not include a coolingfan could apparently not be used with this device. In addition,reversible cutting blades pose a greater threat of injury to theoperator than a softer material, such as a trimming string.

Further, many lawn equipment operators use a string trimmer for basicedging by rotating the handle of the string trimmer so that the stringrotates in a generally vertical plane and the end of the string strikesthe ground adjacent to a sidewalk or the like. To use a string trimmerin this manner is typically a very awkward operation that places themotor close to the operator's head and requires a back bendingcontortions that are uncomfortable and may be unsafe. When aconventional string trimmer is turned 90° more-or-less to present therotating trimming string in a roughly vertical plane, the enginenaturally rotates along with the drive shaft and the trimmer head, oftenmoving the piston lower than the crankcase, allowing excess oil to enterthe combustion chamber, thereby increasing pollution and denyingsufficient lubrication to the piston rod and crankshaft, and thisrotation frequently places the muffler adjacent to the operator's head,which can cause hearing loss and burns. A string trimmer or the likethat could easily be adjusted to allow comfortable use with the rotatingstring in a vertical plane would be a welcome improvement, especially ifit could maintain the motor or engine in its normal upright position,but none appears to be available, as would a lawn care apparatus thatcan be easily adjusted for convenient use by either a right-handed or aleft-handed operator. Further, in some applications, it may be desirablenot to have the blower operating, which would increase the engine poweravailable to drive the trimmer string, or to be able to regulate thevolume of air expelled by the blower, independently of the enginethrottle or engine speed.

Utilizing a string trimmer for trimming vegetation, typically grass,adjacent to curbs, sidewalks, driveways and so forth has become common.Operators typically rotate the tool in some attitude designed to turnthe rotating string into a basically vertical plane so that onlyvegetation immediately adjacent to the non-vegetation surface is cut. Inusing the string trimmer as an edger, the usual goal is to cut theoffending vegetation at the ground, eliminating grass overhang onto thenon-vegetation surface. Twisting a conventional tool to move therotating string into a vertical plane leaves the operator contorted intoan unnaturally bend posture, typically with the engine immediatelyadjacent to his head, where noise and air pollution are a problem, andthe operator is typically forced to walk backward if he is to see hiswork, creating a danger of being hit by passing motor vehicles that hecan neither see nor hear. The electric motor or gasoline engine alsorotates because it is rigidly connected to the drive shaft housing. Inthe case of a gasoline engine string trimmer, rotating the engine canresult in crankcase oil finding its way into the combustion chamber,causing the engine to bog down or stall and shortening the life of thesparkplug and the engine.

Some string trimmers now have a split boom, or drive shaft housing, thatallows the lower end portion, with the string trimmer attached, to beremoved from the upper boom portion, rotated 90° and then reinsertedinto the upper boom portion, thus rotating the string trimmer into amore or less vertical plane. In order to keep the string trimmer in avertical plane, however, the operator must still contort his body intoan unnatural and uncomfortable position and typically must walk backwardin order to see his work.

This outcome when using a conventional string trimmer as an edgerresults from the industry's misunderstanding the problem it isaddressing. The industry perceives that the problem is rotating thetrimmer string plane in two-dimensional xz space, that is, moving ahorizontal plane into a vertical plane, that is, a simple 90° rotationclockwise for a right-handed operator or counterclockwise for aleft-handed operator.

In reality, the rotation must be considered in three-dimensional xyzspace because the entire lawn care apparatus is being rotated, notsimply the working head and so the orientation of the drive shafthousing and handles changes when the cutting head and rotating stringare rotated. If the operator is to comfortably convert the trimmer foredging with the trimmer string rotating in a vertical plane, the driveshaft housing must also be rotated in a fashion that will allows theoperator to use a comfortable and safer posture while edging. Thecutting path of the trimming string is the plane in which the trimmingstring rotates during use and is typically either a basically horizontalpath when the apparatus is used for trimming turf or a basicallyvertical plane or path when used for edging, in contrast to the walkingpath, which is the route or manner of walking, such as forward orbackward, that the operator takes during lawn grooming operations,either trimming or edging. It is also highly desirable to edge alongcurbs, sidewalks and the like while moving toward the interior of thelawn for lawn trimming chores and then returning over the areas thathave been edged to blow debris back onto the lawn.

Therefore, there is a need for a single lawn care apparatus that can beused as string trimmer, blower and edger; that will perform thesefunctions as well as traditional separate tools; that provides superiortrimming as a result of the simultaneous blower function; that can use avariety of conventional string trimmer heads; that can be easilyadjusted to allow the operator to comfortably operate the trimmingstring in a vertical plane without changing the operator's posture orposition through manipulation of a handle that facilitates comfortableand safe operation of the string trimmer as an edger and that keeps themotor upright; that allows the volume of air expelled from the blower tobe controlled and adjusted independently of the engine speed; and thatcan easily be adjusted for left-handed or right-handed operators.

BRIEF SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providea single lawn care apparatus that can be used as string trimmer, blowerand edger.

It is another object of the present invention to provide a single lawncare apparatus that will perform these functions as well as traditionalseparate tools.

It is another object of the present invention to provide a single lawncare apparatus that provides superior trimming as a result of thesimultaneous blower function.

It is another object of the present invention to provide a single lawncare apparatus that can use either an internal combustion engine or anelectric motor as a power source.

It is another object of the present invention to provide a single lawncare apparatus that can use a variety of conventional string trimmerheads.

It is another object of the present invention to provide a single lawncare apparatus that can be easily adjusted to allow the operator tooperate the trimming string in a vertical plane without changing theoperator's posture or position through manipulation of a handle thatfacilitates comfortable and safe operation of the string trimmer as anedger and that it keeps the motor upright.

It is another object of the present invention to provide a single lawncare apparatus that allows the volume of air expelled from the blower tobe controlled and adjusted independently of the engine speed.

It is another object of the present invention to provide a single lawncare apparatus that can easily be adjusted for left-handed orright-handed operators.

To achieve these objects, the present invention includes an impellerseated in a plenum, preferably a ring plenum, connected to duct work forblowing, and a string trimmer head, both connected to a gasoline engineor an electric motor, or other suitable power source, either corded orbattery operated, through a drive shaft for simultaneous rotation in thesame direction. The blower outlet includes an oval or round shapedoutlet nozzle for concentrating and directing the flow of air from theblower. The rotating string trimmer creates some draft and the air flowfrom the blower creates low air pressure above the rotating string,maintaining the string along a straighter line and a higher line thatwould be the case without the blower's operating and lifting thevegetation to be trimmed, allowing for more even height of the resultingtrimmed vegetation.

A handle is fixed to the drive shaft housing and allows the operator tomove the handle into a variety of different positions that allow theoperator to use the apparatus with the rotating string of the stringtrimmer rotating either a horizontal or vertical plane without changinghis posture or position. The drive shaft housing tube rotates in itsmount adjacent to the engine, while the handle remains fixed to thedrive shaft housing tube and does not rotate independently of the driveshaft housing tube. The adjustable handle also allows adjustment of thehandle so that the apparatus to be used by either right-handed orleft-handed operator using the same posture.

Other objects and advantages of the present invention will becomeapparent from the following description taken in connection with theaccompanying drawings, wherein is set forth by way of illustration andexample, the preferred embodiment of the present invention and the bestmode currently known to the inventors for carrying out their invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is an isometric view of a combination blower, trimmer and edgerfor tending vegetation (lawn care apparatus) according to the presentinvention shown in use for trimming and blowing and utilizing athree-lobed handle on a straight-shaft lawn care apparatus forfacilitating transition of the lawn care apparatus from a trimming to anedging mode.

FIG. 2 is an isometric view of the lawn care apparatus of FIG. 1illustrating the lawn care apparatus in use for edging, which isaccomplished by rotating the three-lobed handle about 135°counterclockwise from the point of view of a right-handed person usingthe lawn care apparatus, which rotates the drive-shaft housing andworking head, but not the engine.

FIG. 3 is an isometric view of the lawn care apparatus of FIG. 1illustrating the lawn care apparatus in use for edging, which isaccomplished by rotating the three-lobed handle 135° clockwise from thepoint of view of a left-handed person using the lawn care apparatus,which rotates the drive-shaft housing and working head, but not theengine.

FIG. 4 is an isometric view of a handle assembly adjacent to the engineand partially cut away to reveal the drive shaft rotation mechanism.

FIG. 5 is an enlarged fragmentary isometric view of the proximal portionof the handle assembly of FIG. 4.

FIG. 6 is an exploded enlarged fragmentary view of the handle portionshown in FIG. 5.

FIG. 7 an exploded fragmentary isometric view of the distal end portionof the handle assembly of FIG. 4.

FIG. 8 is a fragmentary isometric view of the distal end portion of thehandle assembly of FIG. 4 as shown in FIG. 7 shown assembled.

FIG. 9 is a side view of the lawn care apparatus of FIG. 1 that utilizesan alternative embodiment of a handle for rotating the drive shafthousing independently of the engine of the lawn care apparatus.

FIG. 10 is an isometric lower end view of a lawn care apparatusaccording to the present invention and alternative handle embodiment ofFIG. 9 illustrating the rotation of the alternative embodiment handle ofFIG. 9.

FIG. 11 is an isometric view of the alternative embodiment handle ofFIG. 9 shown in the position the handle is in during trimming, that is,with the trimmer string rotating in a basically horizontal plane.

FIG. 12 is an isometric view of the alternative embodiment handle ofFIG. 9 shown in the position the alternative embodiment handle is induring edging, that is, with the trimming string rotating in a basicallyvertical plane.

FIG. 13 is an exploded isometric view of the alternative embodimenthandle of FIG. 9.

FIG. 14 is a bottom view of the housing of the alternative embodimenthandle of FIG. 9.

FIG. 15 is a front view of an air shut-off control lever handle forcontrolling the air flow through the blower of the lawn care apparatusof FIG. 1 by means of a cable running through the drive shaft housing.

FIG. 16 is a side view of the air shut-off control lever handle of FIG.15.

FIG. 17 is a cross sectional view taken along lines 17-17 of FIG. 14showing the arrangement of the gears inside the gear housing of thealternative embodiment handle of FIG. 9.

FIG. 18 is a top view of the blower and trimmer working head of the lawncare apparatus of FIG. 1.

FIG. 19 is a cross section taken along lines 19-19 of FIG. 18 showingthe butterfly air flow cut-off valve in the outlet duct of the blower ofthe lawn care apparatus of FIG. 1.

FIG. 20 is a fragmentary isometric view of the blower and blower airoutlet duct showing the butterfly air cut-off valve in the outlet ductof the blower in the closed position, shutting off the flow of air andpartially cut away to reveal the blower inside the blower housing.

FIG. 21 is an isometric view of the air outlet shut-off valve controllever for use with the lawn care apparatus of FIG. 1 showing the controllever in the position it is in when the butterfly air inlet shut-offvalve in the open position, allowing air to be blown out of the blowernozzle readily during operation.

FIG. 22 is an isometric view of the air outlet shut-off valve controllever for use with the lawn care apparatus of FIG. 1 showing the controllever in the position it is in when the butterfly air inlet shut-offvalve in the closed position, preventing air from being blown out of theblower nozzle readily during operation.

FIG. 23 is a top view of the blower housing and shield assembly of alawn care apparatus according to the present invention showing an airinlet valve and attached control handle, with the air inlet valve shownin the open position, allowing air to be drawn into the blower when theblower is turning.

FIG. 24 is a top view of the blower housing and shield assembly of alawn care apparatus according to the present invention showing an airinlet valve and attached control handle, with the air inlet valve shownin the closed position, substantially depriving the blower of intakeair.

FIG. 25 is a top view of the air inlet valve and control handle of FIGS.23, 24.

FIG. 26 is a user's top view of a lawn care apparatus according to FIG.1 having the alternative embodiment handle of FIG. 9 illustrating theposition of the handle when the lawn care apparatus is used for trimmingby a right-handed operator, that is, with the trimming string rotatingin a basically horizontal plane when used in a right-handed userposition being manipulated into a position suitable for use by aleft-handed operator.

FIG. 27 is a user's top view of a lawn care apparatus according to FIG.1 having the alternative embodiment handle of FIG. 9 illustrating theposition of the handle when the lawn care apparatus is used for edging,that is, with the trimming string rotating in a basically vertical planewhen used in a left-handed user position.

FIG. 28 is a user's top view of a lawn care apparatus according to FIG.1 having the alternative embodiment handle of FIG. 9 illustrating theposition of the handle when the lawn care apparatus is used fortrimming, that is, with the trimming string rotating in a basicallyhorizontal plane when used in a left-hand user position.

FIG. 29 is an enlarged fragmentary view of the handle of FIG. 9connected to the gear box housing of the handle of FIG. 9 illustratingone embodiment of a stop mechanism for controlling rotation of thehandle.

FIG. 30 is a stylized front view of the gear-driven crank handlerotation system of FIGS. 11-13 utilizing an alternative embodiment ofthe rotation stop system best seen in FIG. 29 showing the gear-drivencrank handle rotation system of FIGS. 11-13 of the lawn care apparatusof FIG. 9 locked into position for trimming for a right-handed user.

FIG. 31 is a cross section taken along lines 31-31 of FIG. 30.

FIG. 32 is a stylized front view of the gear-driven crank handlerotation system of FIGS. 11-13 utilizing an alternative embodiment ofthe rotation stop system best seen in FIG. 29 showing the gear-drivencrank handle rotation system of FIGS. 11-13 of the lawn care apparatusof FIG. 9 locked into position for trimming for a left-handed user.

FIG. 33 is a cross section taken along lines 33-33 of FIG. 32.

FIG. 34 is a sectional front end view of the main body portion of thegear driven crank handle system mounted on the drive shaft housing shownin condition for free rotation about the drive shaft housing.

FIG. 35 is an enlarged fragmentary exploded isometric view of the jointmechanism between upper and lower drive shaft housing members, allowingfor different working heads to be used interchangeably with the sameupper drive shaft housing portion and engine.

FIG. 36 is a schematic side view of the lawn care apparatus of FIG. 1shown oriented in an xyz coordinate system.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a combination blower, trimmer and edger for tendingvegetation, that is, a lawn care apparatus, 10 according to the presentinvention includes an elongated tubular drive shaft housing 12 having alower, or distal end 14 with a working head 16 attached to it and anupper, or proximal end, 18 having a motor 20 connected to it. The motor20, which may be either a gasoline engine of four stroke or two-strokedesign, or an electric motor, or other suitable power source, which maybe battery powered or powered by conventional AC power through a cord,rotates a drive shaft housed within the drive shaft housing 12, which isa straight shaft tool as shown in FIGS. 1-3.

Still referring to FIG. 1, the straight shaft version of FIGS. 1-3 ispreferred in commercial turf applications because there is less frictionbetween the drive shaft splines and the drive shaft sleeve inside thedrive shaft housing, resulting in lower operating temperatures insidethe drive shaft housing and longer life. In order for the lawn careapparatus 10 with the straight shaft 12 to present the working head 16to horizontal turf when the lawn care apparatus is held in a normalposition, the angle of direction of the driving forces must be changed,which is accomplished by the two-gear transmission 22, whichconventionally reduces the revolutions per minute (rpm) of the rotatingstring 24 to one-half of the rpm of the engine 20, and reverses thedirection of rotation of the rotating string 24 relative to the engine20 and doubles the torque applied to the rotating string 24. Thetransmission 18 itself generates enough heat to burn the user, butreduces the temperature of the drive shaft. The transmission 18,however, adds significantly to the cost of the overall lawn careapparatus 10, so in light-duty, typically consumer applications, a bentdrive shaft housing, such as that shown in FIGS. 9, 10, allows theworking head 16 to be oriented at basically 90° to the portion of thedrive shaft housing that it is connected to and eliminates the two geartransmission 22, saving the manufacturer money, but providing a toolwith a shorter life. Further, however, the increased friction created bybending the drive shaft heats the drive shaft housing sufficiently toburn the user and heats the internal plastic spline that houses thedrive shaft enough to shorten its life significantly. The presentinvention is adaptable for use with either a straight shaft lawn careapparatus 10 or a curved shaft lawn care apparatus 10.

Still referring to FIG. 1, the rotating crankshaft of the motor 20 istypically connected to a clutch, which drives the proximal end 91 of adrive shaft or cable 90 (see, e.g., FIG. 4, 6), which in turn isoperatively connected at its distal end 25 to a working head 16, such asthe string trimmer head 26. In each embodiment, a drive shaft 90 has aproximal end 91 operatively connected to the engine 20 and a distal end25 operatively connected to a working head 16. A mounting flange 32 isused to mount a shield, such as the shield of FIGS. 9, 10, which hasbeen omitted from FIGS. 1-3 to show the working head 16 more clearly. Ahuman operator who is right-handed, grasps a throttle handle grip, orsleeve, 34, which is adjacent to the lower end of the motor 20, which isfixed onto an upper portion of the drive shaft housing 12, in his lefthand and operates the throttle control trigger 36 with his left-handindex finger. In this position, the gasoline tank cap 38 is locatedfurthest toward the right-hand margin of the drawing, and is physicallyhigher than the gasoline tank.

Orientation of the directional terms left-hand, right-hand, clockwiseand counterclockwise is determined from the point of view of a personstanding adjacent to the engine 20 and facing the working head 16.

Still referring to FIG. 1, the operator grasps the three-lobed handle 40with his right hand. The three-lobed handle 40 includes a top lobe 42having a top hand grip 44, which is slightly curved but substantiallystraight and includes a finger opening 46. The top lobe 42 is theportion of the three-lobed handle 40 closest to the operator when thelawn care apparatus 10 is used for trimming and blowing along asubstantially horizontal surface, as shown in FIG. 1. In this trimmingand blowing mode shown in FIG. 1, the top lobe 42 is naturally presentedto the operator for gripping and no other portion of the three-lobedhandle 40 can be comfortably gripped. The three-lobed handle 40 ispreferably made in two pieces from injection molded plastic, includingan primary section 50 and a fastening section 52 that are fastenedtogether by screws. The three-lobed handle 40 is fixed to the driveshaft housing tube 12 so that these parts can only rotate together, thatis, the three-lobed handle 40 does not rotate independently of the driveshaft housing tube 12.

Still referring to FIG. 1, a left-hand lobe 54 and the right-hand lobe56 are connected by and both include an arcuate hand grip portion 58having a large finger opening 60 along its length. The left-hand lobe 54is further connected to the top lobe 44 by the left-hand spoke 55 andthe right-hand lobe 56 is further connected to the top lobe 44 by theright-hand spoke 57. The fastening section 52 is actually screwed intothe area where the left-hand spoke 55 and the right-hand spoke 57 joinin the middle of the distances between the perimeter point where eachbegins to the approximate center of the three-lobed handle 40. When thelawn care apparatus 10 is in the trimming position shown in FIG. 1,neither the left-hand lobe 54 nor the right-hand lobe 56 can be grippedcomfortably due to the hump 59 on either side of the top lobe 42 thatforces the operator to move the three-lobed handle 40 into a comfortablegripping position, which is also the desired position for a particularuse, e.g., trimming or edging. Left and right are taken from theposition of a person standing behind the motor 20 and facing the lawncare apparatus 10 with the working head 16 directly in front of theperson. Clockwise and counterclockwise are defined from the point ofview of the this same reference person.

Referring to FIG. 2, the three-lobed handle 40 and the drive shafthousing 12 have been rotated together exactly 135° counterclockwise fromthe position shown in FIG. 1, which places the rotating string 24 into asubstantially vertical plane, as shown, while the motor 20 remains inthe same position as shown in FIG. 1, that is, with the gasoline tankcap 38 being the portion of the motor 20 that is closest to theright-hand drawing margin. The stationary upright position of the motor20 is accomplished by allowing the drive shaft housing 12 to slip abouta sleeve at its proximal end adjacent to the motor 20, an arrangementdiscussed in detail in relation to FIGS. 4-8. The ability to retain themotor 20 in a stationary upright position ensures that the motor 20remains in its desirable operating normal basically upright position,that is, with its crankcase lower than the piston and with the exhaustpipe away from the operator's face. This 135° counterclockwise rotation,as indicated by the directional arrow 62 also presents the right-handlobe 56 for comfortable gripping and this rotation is used for by aright-handed operator. This rotation also moves the working head 16 outto the right side of the operator somewhat, allowing the operator towork comfortable while moving forward, allowing him to view the workarea easily and to see oncoming motor vehicle traffic.

Still referring to FIG. 2, in common practice operators remove theshield from a straight shaft trimmer, thereby removing the stringcutting tool and they allow the trimmer string 24 to become very long,for example 0.6-1 m (2-3 feet) in order to see the end of the trimmerstring 24 better. The longer trimmer string places extreme loads on theengine 20 and the bearings. Further, it basically converts the rotationof the trimmer string 24 from a horizontal plane to a horizontal planeinto a two dimensional rotation problem rather that a three dimensionalrotation problem because the apparatus 10 resembles a long axis cuttingtool such as a chainsaw. In this case, a rotation of the drive shafthousing 12 of about 90° serves to convert the apparatus 10 from atrimming mode to an edging mode.

Referring to FIG. 3, the lawn care apparatus 10 has been similarlyrotated, but 135° clockwise, as shown by the directional rotationalarrow 64, which is the direction of rotation for a left-handed user, whowill naturally grip the throttle handle grip 34 with his right-hand andthe now presented left-hand lobe 54 of the three-lobed handle 40 withhis right hand. The motor 20 remains in its normal basically uprightposition as described in relation to FIG. 2 above, with the working head16 being projected somewhat to the left of the left-handed user,allowing him comfortably to walk forward while edging and to view boththe work area and oncoming traffic while the rotating string 24 rotatesin an essentially vertical plane, as shown in FIG. 3.

Referring to FIG. 4, the throttle grip housing 34 is fixedly connectedat its proximal end 66 to a conical shaped clutch housing 68, which hasfour bosses 70 for attaching the engine 20. The throttle grip housing 34is formed from a right-hand shell member 72 and a mating left-hand sideshell member 74 (FIG. 1) that are fastened together by tightening screwsinto the screw fittings 76, creating a top seam 78 and a bottom seam 80.The throttle grip housing 34 is shown with a top and bottom seam 78, 80for purposes of clarity and this construction is commonly in the art,but it is preferable to provide seams on the left-hand a right-handsides of the throttle grip housing 34 so that when the user grasps thethrottle grip housing 34 there is no chance that the seams will open up,which can pinch the user's hand. The drive shaft housing 12 is insertedinto the hollow body of the throttle grip housing 34 so that itsproximal end 82 abuts the clutch housing 68. The drive shaft housing 12is firmly seated in the throttle grip housing 24, but can be rotatedinside it by firmly twisting the drive shaft housing 12 relative to thethrottle grip housing 34. The engine 20 is fixed to the clutch housing68 and the working head 16 is fixedly connected to the distal end of thedrive shaft housing 12, so when the drive shaft housing 12 is twistedrelative to the throttle grip housing 34, the working head 16 rotateswith the drive shaft housing 12 and the engine 20 does not. Thisarrangement works in the same fashion with either a curved shaft ofstraight shaft lawn care apparatus 10.

Still referring to FIG. 4, to limit the rotation of the drive shafthousing 12 and to prevent it from being unintentionally removed from thethrottle grip housing or sleeve 34, a limiting slot 84 is formed intothe drive shaft housing 12 immediately adjacent to its distal end, abouta portion of the circumference of the drive shaft housing 12 and arotation guide and limiting screw or other stop member 86 is insertedinto a threaded aperture 88 in the bottom of the throttle grip housingand fixed therein so that the rotation guide and limiting screw 84penetrates the limiting slot 84. The rotation guide and limiting screw84, or other suitable limiting stud or the like, must be short enough sothat it does not interfere with the drive cable or drive shaft 90 andguides the rotation of the drive shaft housing 12 to prevent the driveshaft housing 12 from being pulled free from the engine 20, slippingdownward, or so forth, which may cause drive failure. Proximal end 91 ofthe drive shaft or drive cable 90 is connected to the engine 20, and maybe operatively connected to a clutch between the engine 20 and theproximal end 91.

Still referring to FIG. 4, the throttle control trigger 36 include apivot point peg 92 fastened into the throttle grip housing 34 and anaperture 94 that receives a hooked end 96 of the throttle cable 98, withhooked proximate end 100 of the throttle cable 98 being inserted into acorresponding aperture on the throttle of the engine 20.

Referring to FIG. 5, the left-hand end 102 of the limiting slot 84 stopscounterclockwise rotation of the drive shaft housing 12 as shown by thecounterclockwise rotational directional arrow 104 when it butts into thelimiting screw 86 and the right-hand end 106 of the limiting slot 84stops clockwise rotation of the drive shaft housing 12 when it buttsinto the limiting screw 86 when rotated clockwise as shown by theclockwise rotational directional arrow 108. Total rotation allowed bythe limiting slot lies in a range of 110°-160°, with the stronglypreferred range of rotation being 135°, as shown enlarged in FIG. 6. Therotation of the drive shaft housing 12 independently of the throttlehandle grip 34 and the engine 20 is utilized by the lawn care apparatus10 with the three-loped handle 40 of FIG. 1, the crank operated geardriven handle of FIG. 9, or any other type of handle.

Referring to FIG. 7, an alternative embodiment throttle handle grip 110formed from an upper clamshell half 112 and a mating lower clamshellhalf 114 fastened together by adhesives or other suitable fasteners toclamp the drive shaft housing 12 firmly while still permitting rotationof the drive shaft housing 12 independently of the throttle handle grip110 utilizing the slot 84 mechanism described above. A set screw 116 isinserted through an aperture in a cam lever lock 118 and is received andtightened into the threaded aperture 120 in the upper clamshell half112. A cam surface 122 on the cam lever lock 118 is pressed against acam receiving fitting 124 in the aperture 126 in the lower clamshellhave 114 such that when the cam lever handle 128 is turned in thedirection of the arrow 1140 (FIG. 8), the upper and lower clamshells112, 114, the upper and lower clamshells 112, 114, are clamped togetherfirmly enough that the drive shaft housing 12 cannot be rotated withinthe throttle handle grip 110 with normal effort, that is, the driveshaft housing 12 is locked into the rotated position it was set to priorto turning the cam lever 128. To release or unlock the cam 120 and allowrotation of the drive shaft housing 12 relative to the throttle handlegrip 110 again, the cam lever 128 is turned in the opposite direction asshown by the arrow 130 in FIG. 7.

Still referring to FIG. 7, each clamshell half 112, 114, includes aplurality of upstanding reinforcing ribs 132, each having a concavecurved surface 134 that defines a semi-circle and that grip the driveshaft housing 12 when the upper clamshell half 112 and the lowerclamshell half 114 are joined together as shown in FIG. 8 and a flatleft-hand flange portion 136 and a flat right-hand flange portion 138.These reinforcing ribs strengthen the throttle handle grip 110 anddampening vibrations in the drive shaft housing 12 during operation.

Referring to FIG. 8, the assembled throttle handle grip 110 isillustrated, showing the locking action of the cam lever lock 118.

Referring to FIG. 9, a gear-driven crank handle shaft rotation system142 (crank handle system) is mounted onto the drive shaft housing 12 inthe same fashion as the throttle handle grip 110 of FIG. 8, 9 and islocated below the throttle grip 34 or 110 and at the approximatelongitudinal center of gravity. The crank handle system 142 includes ahousing 144 and a handle 146 protruding from the housing 144. When thelawn care apparatus 10 is in the trimming position, that is with thetrimming string 24 and the debris shield 148 basically horizontal, thegrip portion 150, which is covered by the high-friction rubber comfortgrip 151(best seen in FIG. 10) of the handle 146 is horizontal while theextension arm portion 152 of the handle 146 projects upward from thedrive shaft housing 12 and is basically perpendicular to it. The housing144 has a two-piece clamshell structure that grips the drive shafthousing 12 (e.g., FIG. 13) firmly enough that the drive shaft housing 12rotates with it, that is, the housing 144 and the connected crank handle146 cannot turn independently of the drive shaft housing 12, while thedrive shaft housing 12 can rotate independently of the engine 20 usingthe structure shown in FIGS. 4, 5, discussed above.

Still referring to FIG. 9, a blower housing 154 enclosed a ring blower,or impeller, 155 that is operatively connected to the distal or lower,end 14 of the drive shaft housing 12 and includes an air outlet duct 156having a top wall 158 and a bottom wall 160, which are closer togetherat the outer edge 162 of the air outlet duct 156, that at the blowerhousing 154, as are the left-hand side wall 164 and the right-hand sidewall 166 (FIG. 10) of the air outlet duct 156, providing a nozzle with aventuri effect that accelerates the air moving through the air outletduct 156 as it passes through the nozzle or air outlet duct 156. Thering blower, or impeller, 155 is superior to the commonly used volute orspiral blower because the ring blower, or impeller, 155 occupies asmaller volume, while maintaining high velocity and high volume airflow, thereby not interfering with the trimmer string 24 or theoperator's sight lines. The same constricted nozzle design is retainedregardless of the general shape of the air outlet duct, which may beconical, oval, etc.

Still referring to FIG. 9, a the point 170 defines the origin of a threedimensional space conveniently plotted as the xyz space 171 and definesthe center of the trimmer string 24, with a first portion 172 and asecond portion 174 having equal lengths and spanning a total distancefrom the first portion tip 176 to the second portion tip 178 preferablylying in a range of about 30-76 cm (12-30 inches), with the preferredlength being 43 cm (17 inches). The trimmer string 24 may be one lengthof string as utilized in some types of string trimmer heads or twoseparate lines as shown in, for example, FIG. 9, or more than twoseparate strings. During operation, all strings will be cut to equallength because the debris shield 148 includes a line cutter.

Still referring to FIG. 9, the air outlet duct 156 and its outlet edge162 are aimed downwardly to direct the air flow at the outer tip ends176, 178 of the trimmer string 24, thereby increasing and maximizing thedebris dispersion capability of any particular lawn care apparatus 10for any given size of motor or engine 20 and reducing or eliminating thelift imparted to the rotating string 24 by air blowing over the trimmerstring 24. When the outlet nozzle is parallel to the trimmer string 24,the lift imparted due to Bernoulli's principle is considerable, causingthe rotating trimmer string to depart from its otherwise planarrotation, thereby placing excess strain on bearings and the like,wasting engine power, decreasing the effectiveness of the trimmingfunction and reducing operator control over the height of the cut beingmade.

Referring to FIG. 10, the handle 146 includes a stem portion 180 thatprotrudes from the housing 144 of the crank handle system 142 and isconnected to a gear inside the housing 142, as described below. The stemportion 180 can be rotated about its own longitudinal center line fromits neutral equilibrium position shown in FIG. 9 in either a clockwisedirection (as seen from a position looking down on the stem portion 180)as shown by the arrow portion 182 or clockwise (as seen from a positionlooking down on the stem portion 180) as shown by the arrow portion 184of the double-headed directional arrow 186, which allows a totalrotation of the stem portion 180 in a range of 105°-165°, with thepreferred rotation being 135°, with one-half of any rotation beingclockwise of the equilibrium or neutral position and one-half of anyallowed rotation being counterclockwise of the neutral position.

Still referring to FIG. 10, the stem portion 180 has been rotated 135°in the direction indicated by the directional arrow 188 in FIG. 9, thatis, by the operator's pulling the handle grip 151 back toward himself,thereby rotating the rotating string 24 into a vertical plane on theuser's left-hand side, resulting in the handle 146 being rotated intothe position shown in FIG. 10, while maintaining the engine 20 in itsnormal upright position. With the handle 146 in the position shown, thestring trimmer head 26 is also moved outward to the user's left side,thereby allowing the operator to hold the lawn care apparatus 10 in anatural position substantially identical to the position used fortrimming in a horizontal plane and allowing the operator to walk forwardwhile edging and easily maintaining a straight line that he can seethroughout the operation, while also seeing oncoming traffic.

Referring to FIG. 11, the housing 144 includes a locking set screw 190that permits easy manipulation of the rotating handle 146 when loosenedand locks the handle 146 into its desired position when tightened. Asshown, the handle 146 is in its normal position for trimming, with therubber grip 151 above the housing 144.

Referring to FIG. 12, the handle 146 has been rotated about the stemportion 180 in the direction of the directional arrow 192 by 135° torotate the housing 144 toward the viewer by 90°, presenting the bottomsurface of the housing 144 as the portion of the housing 144 closest tothe viewer. Since the working head 116 is rigidly connected to the driveshaft housing 12 and, through it, the housing 144, the working head 14has also been rotated 90°, as shown in FIG. 10. This rotation of thehousing 144 also exposes to view the air flow shut-off control lever194, which is connected to the housing by the rivet 196, allowing theoperator to move the control lever 194 between an on position and an offposition or any intermediate position through a cable 198, which may berun along the outside of the drive shaft housing, or, in the case of anon-split boom tool, inside the drive shaft housing, and shut off valvesystem shown in detail in FIGS. 20-21. This air shut off valve allowsthe user to select the desired volume of air expelled from the blowerhousing 154.

Referring to FIG. 13, the stem portion 180 includes a proximal end 198that is fastened to stop member collar 200 and then to a first 45°beveled gear 202 having an access parallel to the stem 180 and whichmeshes with a mating second 45° beveled gear 204 that is rigidly mountedonto the drive shaft housing 12, which passes through the hole 206 inthe mating 45° beveled gear 204. Each beveled gear 202, 204 is moldedfrom tough durable nylon and has thirty-three teeth, or other 1:1 gearratio, so that turning the stem portion 180 resulting in a 1:1 rotationof the drive shaft housing 12. Rotation of the stem portion 180 islimited by the stop collar disk 205, which includes a recessed landportion 207 that extends over 135° of the stop disk 205, with the stoprod 211, fastened to the stem portion 180, bumping into the resultingupstanding flange portion 209 at either end of the allowed range ofrotation, as discussed in more detail below in connection with FIG. 29.

Still referring to FIG. 13, the housing 144 includes an upper clamshellmember 208 and mating lower clamshell housing member 210 that form ahorizontal seam 212 when clamped together by the rear set screw 214 andthe forward set screw 216, and to conceal and protect the two beveledgears 202, 204. Each clamshell member 206, 208 includes about twelveupstanding reinforcing rib portions 218, each having a semi-circularrecess portion 220 that fits against the outer surface of the circularcross section drive shaft housing 12 firmly to hold the housing 144firmly against the drive shaft housing 12. The midpoint of thesemi-circular recess of each reinforcing rib portion 218 is in thecenter of the distance between the outer edges of the width of theclamshells 208, 210. Each reinforcing rib portion 218 also includes aleft and right hand flat outer flange portions 222. These portions arealigned with one another on the upper and lower clamshell members 208,210 and contact each other when the two clamshells 208, 201 are broughttogether. The reinforcing rib portions 218 strengthen the housing 144and dampening vibrations in drive shaft housing 12 during operation,increasing operator comfort and reducing the likelihood of carpal tunnelsyndrome in operators. Three stem housing ribs 224 perform the samefunctions in the stem housing portion 226 of the housing 144 thatextends outwardly and perpendicularly to the main housing body 228 toprovide support for the stem 180 portion of the handle 146.

Still referring to FIG. 13, the throttle-like air valve control lever194 is held in the bracket 230, which includes a circular lid portion232 and a stem-like fastening portion 234 that is fastened to thehousing 144 by screws or the like.

Still referring to FIG. 13, the length of the extension arm portion 152of the handle 146 can be adjusted to accommodate comfortably differentheight operators by pressing the spring release button 236, therebyreleasing a spring-loaded locking button that is seated in a selectedone of the adjustment apertures 238 in an outer end portion 240 of theextension arm portion 152. The proximal end 242 of the outer end portion240 is received into the cylindrical coupling member 244 and can be setin its desired length by the operator. The lower end portion 246includes a distal end 248 that is received into and rigidly fixed to thecylindrical coupling member 244 and the outer end portion 240 fitsinside the lower end portion 246, which has a slightly larger diameter.This adjustment mechanism allows comfortable upright operating posturesfor virtually any height operator.

Still referring to FIG. 13, the angle between the grip portion 150 andthe outer end portion 240 of the handle 146 is 90° as indicated by thedouble-headed arcuate arrow 2239 and both of these parts of the handlelie in the same plane, that is, it is formed by bending a tube 90° atthe appropriate point. The angle between the stem portion 180 and thelower end portion 240 of the handle 146 is 110° (?) As indicated by thedouble-headed arcuate arrow 241.

Referring to FIG. 14, the throttle-like air control lever 194 can beadjusted at any point along an arc of 105° as indicated by thedouble-headed arrow 250 from the fully closed position 252 to the fullyopen position 254.

Referring to FIG. 15, the throttle-like air control lever 194 can be setinto a plurality of discrete positions by setting one of the indexingapertures 256 formed into the circular control plate 258 that isconnected to the air control lever 194. The indexing apertures 256 setover a small setting nub in the lid portion 230 of the bracket 230.

Referring to FIG. 17, a compressed coil spring 260 applies force to thecircular control plate 258, keeping the throttle-like air control lever194 in the desired position set by the operator.

Referring to FIG. 18, an open web 262 of air inlet openings 264 allowsair to be drawn into the top of the blower housing 154 when the blower,or impeller 155 is rotating, which is expelled through the air outletduct 156. The open web 262 allows for vigorous air flow, whilepreventing debris, such a sticks, from being drawn into the blowerhousing 154, which might otherwise be hurled dangerously. The debrisshield 148 preferably includes an outer arcuate perimeter 263 and a pairof outer wing portions 265, which block additional debris and areoutside the width of the fan portion 267 that becomes progressivelynarrower as it comes closer to the blower housing 154, to which it isconnected.

Referring to FIGS. 19, 20, the throttle-like air flow regulating, orcontrol, valve 266, set into the outer edge of the air outlet duct 156and retained by the pins 270, is urged by the spring 268 into the closedposition shown in FIG. 20, in which the outlet opening in the air outletduct 156 is substantially blocked. When the operator pulls on the cable197, the throttle-like air flow control valve 266 is progressivelyopened, until the butterfly valve portion is essentially parallel to theupper and lower walls 158, 160 of the outlet duct or nozzle 156,maximizing air flow through the blower housing 154. Alternatively orsimultaneously, the air flow through the blower housing 154 may beprogressively reduced or increased or essentially shut off by a valvemechanism at the air inlet open web 262, as shown in FIGS. 23-25 anddiscussed below.

Still referring to FIG. 19, shows the throttle-like air flow controlvalve 226 in the closed position, substantially shutting off the airflow, which is accomplished by rotating the throttle-like air flowcontrol valve 226 in the direction of the arrow 274 by pulling on thecable 197 sufficiently to overcome the tension of the spring 268.Letting off on the cable 197 allows the spring 268 to move thethrottle-like air flow control valve 226 in the direction of the arrow276, thereby progressively and selectively opening the control valve226.

Decreasing the air flow through the blower 155, through manipulating thevalve 266 or a valve in the open web 262, or both, increases theproportion of engine 20 power available to drive the trimmer string 24because the work being performed by the blower, or impeller, 155 isreduced, as is the volume of air passing through the blower, orimpeller, 155. This effect is maximized when the air flow through theblower, or impeller, 155 is substantially closed off. Even with the airflow control valve 266 in the fully closed position, however, some airis moved by the blower, or impeller, 155, which draws air through thehollow tubular drive shaft housing 12, cooling it, thereby preventingoverheating and extending the life of the drive shaft cable 90 andassociated bearings or sleeves. In curved shaft string trimmers, heatbuildup in the general area of the curve in the drive shaft housing isconducted to a spool of plastic trimmer string and heats the trimmerstring enough to partially melt it, welding the reserve supply oftrimmer string to itself, a common and aggravating problem whollyovercome by the blower, or impeller, 155 as described.

Referring to FIG. 20, a guard bracket 278 includes an outer guardportion 280 connected at one end to a left-hand leg portion 282 and aright-hand leg portion 284 which are substantially parallel to oneanother and substantially perpendicular to the outer guard portion 280and each of which includes an inwardly projecting fastening end portion286, that snap into aligned apertures in the air outlet duct 156. Theguard bracket 278 helps protect the air outlet duct 156 from damage fromdragging or banging, which is more likely when the lawn care apparatus10 is used for edging by a left-handed operator, which results in theair outlet duct 156 being close to the ground and therefore susceptibleto damage. The guard bracket 278 is preferably made from heavy gaugespring steel.

Referring to FIG. 21, in an alternative air-flow valve control lever foropening, closing or setting an intermediate opening of the throttle-likeair flow control valve 266, a pivoting handle 288 is connected to thedrive shaft housing 12 by the clamshell bracket 290, which is secured bythe nut and bolt 292. The cable 197 has a ball fitting 294 in its end,which locks the cable 197 into the cable lock aperture 296 on the handle288. In this embodiment, the cable 197 runs along the outside surface ofthe drive shaft housing 12, which is necessary when the lawn careapparatus includes a split boom construction that allows differentworking heads 16 and attached lower boom portions to be connected to thesame upper boom portion and engine, as shown in FIG. 30. Thethrottle-like air shut off valve 266 is in the closed position when thehandle 288 is in the position shown in FIG. 21 and is allowed to beopened by spring force when the operator pulls back toward himself inthe direction of the arrow 298 in FIG. 22, causing the cable 197 to goslack.

Referring to FIGS. 23-25, an air inflow regulating, or control valve,300 in the top 302 of the blower housing 154 includes seven fan shapedblades 304 each having a narrow end connected to a circular hub 306having an aperture 308 in its center. An elongated control handle 310 isconnected to the fan shaped blade 312, which allows the air inflowcontrol valve 300 to be rotated easily. Adjacent to a proximal end 314of the control handle 310 includes a locking slot 316 that locks the airinflow control valve 300 into the operators desired position when it anyof the indexing nubs 318 on the top surface 320 of the debris shield 148penetrates the locking slot 316.

As shown in FIG. 23, the air inflow control valve 300 is open, so thatthe fan shaped blades 304 align with and are physically above the matingseven baffles 322 in the air inflow guard 324 of the blower housing 154,allowing for maximum air intake.

Referring to FIG. 24, the control handle 310 has been moved in thedirection of the arrow 326, providing the closed sealed appearance ofthe seven baffles 322 in the air inlet itself and the seven fan shapedblades 312, which together cover the entire circular air inlet systemfor the blower, or impeller, 155, substantially closing off the airsupply to the blower, or impeller, 155, reducing the work it performsand its load on the engine 20, allowing more engine 20 power to beapplied to the trimmer string 24, and so forth as discussed above inconnection with FIGS. 18-20. The control handle 310 can be adjusted toany intermediate position between a valve fully opened and a valve fullyclosed position in basically infinite increments as selected by theoperator. Both types of air control valves disclosed herein can be usedsimultaneously on the same lawn care apparatus 10 having a blower andstring trimmer on the same tool. In many trimming applications, forexample, along a fence in a grass yard, blowing debris away is notneeded or desired and in these cases it is beneficial to cut off thesupply of air to the blower, or impeller, 155 or to cut off the flowthrough the air outlet duct, or both.

Referring to FIG. 26, the handle housing 144 is rotated is rotated 180°clockwise relative to the drive shaft housing 12, with the handlehousing 144 being loosened prior to rotation, as indicated by the arrow328 to move the handle 146 into position for use by a left-handedoperator, moving the handle 146 along the direction of the arrow 330.The starting position is shown in FIG. 25, in which the debris shield148 is essentially horizontal and closer to the operator than the airoutlet duct 156.

Referring to FIG. 27, the lawn care apparatus 10 has been moved intoposition for use in edging by a left-handed operator, in which thedebris shield 148 is basically vertical and the air outlet duct is notvisible because it is the lowest par of the blower housing 154. Thisposition is achieved by rotating the handle 146 in the direction of thearrow 332, which rotates the drive shaft housing 12 in the direction ofthe arrow 334 so that the rigidly connected debris shield 148 rotatesinto the essentially vertical plane shown. The set screws 214, 216 areloosened to permit rotation of the handle 146 relative to the driveshaft housing without moving the drive shaft housing 12 relative to theengine 20 and are tightened to lock the handle housing 144 146 rigidlyonto the drive shaft housing 12 when the desired orientation of the mainhousing body 228 has been achieve.

Referring to FIG. 28, the lawn care apparatus 10 is shown after beingmoved into position for left-handed use in the trimming mode, with thehandle 146 on the right-hand side of the drive shaft housing 12 and thedebris shield 148 basically horizontal, which is the position achievedthrough the manipulation indicated in FIG. 27.

Referring to FIG. 29, the stop collar disk 205 allows the stem portion180 of the handle 146 to be rotated along the directions of thedouble-headed arrow 336 through a range of 135° between the upper stopflange portion 209 and the lower stop flange portion 338, with the stoprod 211 bumping the upper stop flange 209 when the lawn care apparatus10 is in the trimming position for a right-handed person, as in FIG. 9,and bumping against the lower stop flange 338 when the lawn careapparatus 10 is in the edging position for a right-handed operator, asshown in FIG. 10.

Referring to FIG. 30, 31, the stem portion 180 of the crank handle 146includes an upper toggle latch, or trimming latch and stop member, 340connected to the housing 144 by the pivoting connection 342 in itscenter. A channel 344 along the lower surface of the upper toggle latch340 includes left side and right side upstanding walls that serve asstops when butted against by the alien wrench stop screw 346. Theoperator can press down on either end of the upper toggle latch 340 toallow the housing 144 to clear the top of the set screw 346 and permitrotation of the housing 144 about the drive shaft housing 12 untilanother desired position is achieved, such as the position shown inFIGS. 32, 33 and used for left-hand operators who are trimming.Similarly, an edging mode toggle latch and stop member 348 is pivotallyconnected to the outer surface of the housing 144 at the pivot point350. To move the lawn care apparatus 10 from the trimming to the edgingposition by releasing the trimming latch and stop member 340, rotatingthe housing 144 and then depressing the relevant end of the edging modetoggle latch and stop member 348 to raise it and to allow the alienwrench stop screw 344 to enter the edging mode locking channel 352, thenreleases the edging mode toggle latch and stop member 348, locking thehousing 344 into the edging mode. The crank handle 146 is also rotatedas described above. If desired, as shown in FIG. 34, the alien wrenchstop screw 344 can be recessed below the outer surface of the housing144 to permit full and free rotation of the housing 144 about the driveshaft housing 12 in response to cranking the handle 146. For any use ofshort duration, this is the preferred mode because frictional lossesthroughout the system will prevent undesired rotation of the housing 144relative to the drive shaft housing 12 in most applications.

Referring to FIG. 35, in an alternative embodiment, the drive shafthousing 12 and the drive shaft cable 90 have been cut in two at a pointbelow the lower end 353 of the housing 144, creating an upper boomsection 354 and a lower boom section 356. Protruding from the lower boomsection 356 is a drive shaft square end fitting 358, mates with therecesses drive shaft socket 360, recessed into the distal end 361 of theupper boom section 354. The lower boom section 356 slides inside thelower end of the upper boom section 354 until the drive shaft square endfitting 358 mates with the recessed drive shaft socket 360. Thepositioning button 362, slightly spring biased upward by the springstrip 364 it is fastened to, with the spring strip 364 in turn fastenedto the lower boom section 356 by the rivet 365, springs into the neutrallocating aperture 366, signifying to the operator that full engagementof the shaft parts has been achieved and that the apparatus is inposition for trimming by a right-handed user. Then the operator tightensthe clamp adjustment screw 368, in turn tightening the drive shafthousing clamp 370 and securing the upper and lower boom sections 354,356 together firmly in an operating position.

Still referring to FIG. 35, loosening the clamp adjustment screw 368allows the operator to substitute a different lower boom section 356having a different and perhaps different style of working head on it,for example, a wire brush cutter or saw, or to rotate the lower boomsection 356 relative to the upper boom section 354 so as to achieve adifferent angle between the operating plane of the working head and theupper boom section 354 and the engine 20. In this connection, it isconventional to rotate the lower boom section 56 90° clockwise relativeto the upper boom section 354 and to locate the locating button into theassociated 90° rotation locating aperture 372. Preferably, however, forthe reasons detailed above, the lower boom section 356 should be rotatedand then relocated with the positioning button 362 set into the 135°locking aperture 374, which is 135° clockwise from the neutral positionlocating aperture 366, as indicated by the 135° rotation arrow 376. Forleft-handed use with a straight shaft tool, the lower boom section 356is rotated to align with the negative 135° locating aperture 378, withits location indicated by the negative 135° rotation arrow 380.

Referring to FIG. 36, there is shown a schematic view of the lawn careapparatus 10 shown oriented in three dimensional space plotted on an xyzcoordinate system. The center of trimmer string 24 in the working head16 is at the origin of the xyz coordinate system 382 and the rotatingstring 24 rotates in the xy plane, that is, in the trimming positionparallel to the ground. To achieve a rotating trimming string rotatingin the xz plane, that is truly vertically, the lawn care apparatus mustbe rotated in three dimensional space and not rotated merely in a singleplane, which is typically done. Rotation of such tools to date involvesrotating the entire tool about the axis formed by its own drive shafthousing, i.e., in a polar coordinate fashion treating either end of thedrive shaft housing as the origin. Not only does this rotation lead toan improper rotation, but it places the engine in an unsatisfactoryorientation in which engine oil may find its way into the combustionchamber, as previously noted. To achieve the three dimensional rotationaccording to the present invention, the middle of the trimming string 24is rotated 45° in the xy plane and simultaneously rotated 90° in the xzplane and these rotations are additive about the drive shaft housing 12,leading to a drive shaft housing rotation of 135° and a rotation of thehandle 146 135° about the stem portion 180. Rotation of objects in threedimensional space is treated in Euler's rotation theorem, which has beenused and adapted to work out the rotational aspects of the lawn careapparatus 10.

More particularly, hand-held power tools were originally designed totrim lawns in a two-dimensional xy plane. Then it became more practicalto edge lawns with string trimmers by moving the rotating string into avertical plane. As turf grass management has evolved, landscapers foundthat edging could be easily done while transporting a string trimming orbrush cutting path. This discovery led to a significant reduction in thesale of safer individual power walk-behind edgers and stick edgers thatare set in a two-dimensional vertical position. However, most stringtrimmers and brush cutters continue to be set in a two-dimensionalhorizontal position even though the handle is designed for trimming andedging lawns. Utilizing the combined rotational symmetry ofthree-dimensional power tool features corrects the two-dimensionalproblem.

The most commonly used definition provided for rotational symmetry wasgiven by the mathematical physicist Herman Weyl. Weyl explains thatobjects are said to be symmetrical if one can subject them to a certainrotational operation and the object appears exactly the same after therotational operation as before. Any such operation is said to besymmetrical. Objects that are turned about a fixed center to a newposition so as to appear exactly the same shape must therefore possess acenter line of rotational symmetry. Several objects that are on a centerline of rotational symmetry are said to all possess rotational symmetryif mechanical devices are positioned anywhere on the center line ofsymmetry; such that devices known as gears, levers, wheels, or pulleyscan adjust or transform the objects direction of rotational symmetry. Acombined symmetrical transformation of several objects can beaccomplished by rotating all the individual objects about a given pointon the center line of rotational symmetry. Any starting point [x, y, z]of an object has symmetry if the new transformation point of an object[x y z]=R×(A).Ry(A).Rz(A)*[x, y, z]. In three-dimensional space, R×(A),Ry(A) and Rz(A) must have a given rotation between 0° and 360°.

In summary, several objects can be rotated in symmetry about athree-dimensional xyz axes whereby the sum is equal to the xy horizontalrotation plus the xz vertical rotation. It is common to rotate objectson outdoor power tools from a particular center of rotational symmetry.However, most manufacturers do not account for the extra 1° of xyhorizontal rotation for every 2° of x-z vertical rotation because thereare always two planes (xy and xz) of reflection instead of the singleplane (xy) encountered for trimming. Inconvenient, dangerousconsequences sometimes result from limiting power tool rotationalsymmetry to two-dimensional space.

Any rotation can be given as a composition of rotations about three axes(Euler Rotation Theorem), and thus can be represented by a matrixoperation on a vector through mathematical operations known to the art.

While the present invention has been described in accordance with thepreferred embodiments thereof, the description is for illustration onlyand should not be construed as limiting the scope of the invention.Various changes and modifications may be made by those skilled in theart without departing from the spirit and scope of the invention asdefined by the following claims. For example, a clutch or transmissionmay be interposed between the blower and the string trimmer; tools otherthan a string trimmer, such as cutting blades, saws or the like mayreplace the string trimmer below the blower. Therefore the inventionshould be measured by the claims that follow.

1. A handle for yard trimmer having a shaft, the handle comprising: afastening section configured to secure said handle to the shaft of theyard tool for conjoined movement with the shaft; a top lobe having ahand grip and defining a first finger opening; left-hand and right-handlobes connected by and including an arcuate hand grip defining a secondfinger opening; a left-hand spoke connecting said left-hand lobe to saidtop lobe; and a right-hand spoke connecting said right-hand lobe to saidtop lobe.
 2. The handle of claim 1, wherein said left-hand spoke andsaid right hand spoke extending from said fastening portion.
 3. Thehandle of claim 1, wherein said top lobe is substantially straight. 4.The handle of claim 1, wherein said first finger opening is encircled bysaid top lobe, said left-hand-spoke and said right-hand spoke, andwherein said second finger opening is encircled by said arcuate handgrip, said left-hand lobe, said right-hand lobe, said left-hand spoke,and said right-hand spoke.
 5. The handle of claim 1, wherein said firstfinger opening is smaller than said second finger opening.
 6. The handleof claim 1, wherein said right-hand lobe and said left-hand lobe eachinclude a hump.
 7. A combination yard tool and handle, the combinationcomprising: a yard tool shaft supported for rotation about an axisextending said yard tool shaft between first and second positions; ahandle fixedly attached to said yard tool shaft for conjoined rotationtherewith; and said handle comprising a fastening section fixedlysecuring said handle to said yard tool shaft, a top lobe having a handgrip and defining a first finger opening, a left-hand and a right-handlobe connected by and including an arcuate hand grip defining a secondfinger opening, a left-hand spoke connecting said left-hand lobe to saidtop lobe, and a right-hand spoke connecting said right-hand lobe to saidtop lobe.
 8. The combination of claim 7, wherein said yard tool shaft isrotated into said first position said hand grip is disposed to begrasped by an operator of the yard tool, and said top lobe is disposedso as not to be grasped by the operator, and further wherein said yardtool shaft is rotated into said second position said top lob is disposedto be grasped by the operator and said hand grip is disposed so as notto be grasped by the operator.
 9. The combination of claim 7, whereinsaid left-hand spoke and said right hand spoke extending from saidfastening portion.
 10. The combination of claim 7, wherein said firstfinger opening is encircled by said top lobe, said left-hand-spoke andsaid right-hand spoke, and wherein said second finger opening isencircled by said arcuate hand grip, said left-hand lobe, saidright-hand lobe, said left-hand spoke, and said right-hand spoke. 11.The combination of claim 7, wherein each of said right-hand lobe andsaid left-hand lobe comprise a hump.
 12. The combination of claim 11,wherein said humps are positioned and configured such that graspingeither of said right-hand or said left-hand lobes by an operator causesdiscomfort to the operator, thereby preventing the operator fromgrasping either of said right-hand or said left-hand lobes.
 13. Thecombination of claim 7, wherein said top lobe is substantially straight.